The prohibition of synthetic drugs is like standing on the beach and shouting at the tide to stop rising.

Prohibition of conventional illegal drugs, despite decades of work, hundreds of billions of dollars and thousands of human lives, cannot be called a success. In the past 15 years, the global consumption of cannabis and cocaine has risen by about 50 per cent, while for opiates, it has trebled.

This increase is despite the relative ease in combating such conventional illegal drugs, as opposed to the new synthetics. The new synthetics are often being made in countries where the production is not illegal. They are traded through cyberspace with a speed and anonymity which is only matched by their difficulty of physical detection as they sail through the post, and even the physical bodies of their users, often leaving no trace. They are cheap for the consumer. They are emerging at a rate of about one a week and there is no reason to believe this evolution will plateau as chemists become ever more inventive.

The Psychoactive Substances Act recognised these problems. In a world first, the New Zealand Parliament tried to create a regime that set up a legal framework for the testing, manufacture and regulation of psychoactive substances. In a precautionary manner, the law reversed the onus of proof so the people who want to sell the substances have to prove that they are low-risk before they can be sold.

A number of products were given an interim licence allowing them time to gather their proof. This was where the problem began as evidence started to emerge, and communities began to react, that what was harmless to some people was harmful to others. Prohibition does not reduce demand. It may increase it, as consumers perceive something as "cool" because its status has changed.

The opportunity for the government to tax, provide education and regulate part of the market will be lost. Criminals will make profit and crime will expand.

In short, prohibition of these synthetic drugs risks turning the tragedy of the individual addict into a disaster for society by criminalising them.

The next generation of synthetic drugs will only be allowed to enter the market if they can proven to be low-risk. To be low-risk means they must not be poisonous, addictive, cause cancer, psychosis or other physical failure. But how do we prove something is low-risk.

The answer is through scientific testing on animals. The question of whether lethal scientific experiments on animals are necessary has been a defining social issue for nearly 150 years. Best international practice is in agreement that all scientific experiments on animals should be designed strictly to reduce the number of animals involved, refine the processes to minimise pain and, wherever feasible, replace lethal experiments with non-lethal alternatives.

However, the question of whether such experimentation is necessary is much more vexing.

The majority view is that if the research produces essential results of value to humanity that cannot be produced in any other way, despite its cruelty, it should be permissible. Many countries believe the experimental use of animals in the testing of weapons, tobacco, washing powders or cosmetics is not essential and have banned animal experiments in these areas.

When it comes to the testing of animals with legal drugs, the debate becomes more complicated, as attempts to understand the nature, chemistry and effects of a drug that may have benefits to humanity make many people reluctant to stop animal experimentation in this area.

However, when the studies turn to examine the same factors for illegal drugs which have no benefit to humanity, as occurred in Britain in the past decade, the debate becomes heated as many believe this is unnecessarily cruel. This is because illegal drugs are luxury or trivial items which people voluntarily subject themselves to. Quite simply, the innocent animal should not have to suffer for the choices of the corrupt human.

If the impacts of illegal drugs of any kind ended with the user, this is an attractive answer. However, if the equation is one of trying to prevent the greater costs of prohibition upon society in which the innocent suffer because of misplaced policies, the answer is not so clear-cut.

It is not fair that these costs may fall on other species. But it may be a lesser evil than the alternative, if the goal is to try to find a solution to the problem.